The present invention relates generally to shift levers for effecting gear changing operations in manually operable vehicle transmissions. In particular, the present invention relates to a noise and vibration damper for such a shift lever.
In most vehicles, a transmission is provided in the drive train between the engine and the driven wheels. As is well known, the transmission includes a plurality of gears which are selectively engaged to provide a plurality of speed reduction gear ratios between the input and the output of the transmission. A control member within the transmission is moved by a driver of the vehicle throughout a plurality of gear ratio positions for selecting the desired speed reduction As a result, acceleration and deceleration of the vehicle can be achieved in a smooth and efficient manner.
In many smaller vehicles, such as automobiles, the transmission functions automatically. In other words, the shifting of the control member between the various gear ratio positions in the transmission is accomplished automatically by a control system without any intervention by the driver of the vehicle. However, an automatic transmission is not used in many larger vehicles, such as trucks, because of the increased size and expense Such larger vehicles are, therefore, often provided with a manually operable transmission, one in which the shifting of the control member between the various gear ratio positions is accomplished by physical movement of the vehicle driver.
In order to shift the control member between the gear ratio positions in a manual transmission, a mechanical shift lever assembly is generally provided. A lower end of the shift lever assembly extends downwardly within the transmission into engagement with the control member, while the other end extends upwardly into an area which is convenient for the vehicle driver to grasp and manipulate it. Thus, when the upper end of the shift lever assembly is moved by the vehicle driver, the lower end is also moved within the transmission. By properly moving the upper end of the shift lever assembly, the vehicle driver may position the control member of the transmission to select any one of the plurality of gear ratios for use.
When the vehicle is operated, it has been found that the transmission and other components of the drive train of the vehicle vibrate to a certain extent. Also, vibrations are generated by the vehicle engine itself during operation. All of such vibrations can be sensed as undesirable noise by the vehicle driver. To reduce the amount of this vibratory noise sensed by the driver, the compartment of the vehicle in which the vehicle driver is located is typically lined with acoustical insulating material. Unfortunately, the shift lever assembly must extend upwardly from the transmission into such driver compartment for convenient use. As a result, the shift lever assembly transmits these vibrations into the driver compartment, thereby defeating the acoustical insulation. Thus, it would be desirable to provide the shift lever assembly with a vibration and noise dampening mechanism which reduces or prevents the vibrations of the engine and the transmission from being transmitted by the shift lever assembly into the driver compartment of the vehicle.